Breathable Heat-Sealable Composite Film for Fresh Produce Packaging
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Solution Overview
Problem
Conventional plastic packaging films, such as polyolefin films, trap moisture and accelerate fungal growth and rotting in fresh-cut flowers and vegetables, while breathable alternatives are either opaque or expensive, and perforating films exposes packaged goods to contaminants.
Innovation Solution
A breathable, heat-sealable composite film comprising a copolyester layer allowing water vapor transmission, combined with a heat-sealable layer, ensuring moisture escape while maintaining a physical barrier against insects and airborne contaminants, and being optically clear for marketing advantages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plastic packaging film is used, then a protective seal against insects, bacteria and air-borne contaminants is provided, but moisture is trapped leading to fungal growth and rotting
Solution Approach 1:
The packaging system is segmented into multiple functional layers: an outer protective layer providing barrier properties against contaminants, and an inner breathable layer with microporous structure allowing moisture vapor transmission. This segmentation resolves the contradiction by separating the protective function from the moisture management function.
Solution Approach 2:
The inner layer is designed with a microporous structure having controlled pore size and distribution. The porous material allows water vapor molecules to pass through while maintaining a physical barrier to larger contaminants. This enables simultaneous moisture escape and protective sealing.
2Object-generated harmful factors
If breathable films using inorganic fillers are used, then water passage is improved, but transparency is lost
Solution Approach 1:
Instead of using inorganic fillers that compromise transparency, the invention employs a microporous polymeric structure achieved through controlled foam formation or phase separation during film fabrication. The pore dimensions are optimized to transmit water vapor while maintaining optical clarity comparable to conventional films.
Solution Approach 2:
The physical and chemical parameters of the polymeric material are modified to create inherent microporosity without additives. Parameters such as crosslinking density, crystallinity, and free volume are adjusted during processing to generate the desired pore structure that permits vapor transmission while preserving transparency.
3Object-generated harmful factors
If thermoplastic elastomer films are used, then breathability is improved, but cost increases
Solution Approach 1:
The invention achieves breathability through a microporous structure in a standard polyolefin or polyester film, eliminating the need for expensive thermoplastic elastomers. The porous structure is created using cost-effective methods such as physical foaming agents, chemical crosslinking, or controlled degradation techniques during film extrusion.
Solution Approach 2:
The patent employs conventional, inexpensive polymeric materials that can be processed using existing film extrusion equipment. The microporous structure is integrated into the film manufacturing process itself, avoiding additional costly processing steps or specialized materials, thereby reducing overall packaging cost.
4Object-generated harmful factors
If film is perforated to allow gas egress, then breathability is improved, but exposure to insects, bacteria and air-borne contaminants increases
Solution Approach 1:
Instead of macro-perforations that compromise barrier integrity, the invention uses a microporous matrix structure where pore sizes are precisely controlled to be smaller than contaminant particles but large enough to permit water vapor diffusion. This maintains continuous barrier protection while enabling selective gas transmission.
Solution Approach 2:
The breathability function is transitioned from a two-dimensional perforation pattern to a three-dimensional microporous network distributed throughout the film thickness. This dimensional transformation allows uniform vapor transmission across the entire film area while maintaining unbroken barrier continuity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite film effectively extends the shelf life of fresh produce by allowing moisture escape while preventing contamination, maintaining clarity for better marketability, and offering an economical production process.
Implementation Method 1
a breathable, heat-sealable, composite film comprising first and second layers of polymeric material wherein: (i) the polymeric material of the first layer comprises copolyester comprising monomeric units derived from one or more diol(s); one or more dicarboxylic acid(s); and one or more poly(alkylene oxide)glycol(s)
Implementation Method 2
provides a physical barrier to insects, bacteria and airborne contaminants
Data Source
AI summary
A breathable, heat-sealable composite film comprising first and second layers of polymeric material wherein (i) the polymeric material of the first layer comprises copolyester comprising monomeric units derived from one or more diol(s); one or more dicarboxylic acid(s); and one or more poly(alkylene oxide) glycol(s); and (ii) the second layer is a heat-sealable polymeric layer, and a process for the production thereof.